What happens to the water level of the lake

Imagine you are sitting in a rowboat in the middle of a large lake and have a 50Kg rock in the boat with you. If you throw the rock out of the boat and it sinks to the bottom of the lake, will the water level in the lake go up, go down, or stay the same?

Down. While the rock is in the boat the entire mass of the rock is displaced. When you throw the rock in the water, only a mass of water equal to the volume of the rock is displaced. Since the rock sinks, it does not displace it's mass of water, else it would float

When any one throw the rock,then the boat will through up with the rock mass. In this time water level will equal but after sometimes when boat will came back to water water level will go up.
Thanks

Obviously water level will go up but if the lake or any other water body is very very large then the change in level will be distibuted over whole surface of lake and will be negligible for such small weights as compared to greater surface..